Lub cev muaj ntau zaus welded ncig yog lub voj voos hlau uas tsim los ntawm vuam cov paib hlau) ua ke siv cov nyhuv hlau ua ke ntawm cov nyhuv kub ntawm qhov kev kub siab tam sim no.
Ntxiv nrog rau cov khoom siv welded ntau zaus, nws tseem tuaj yeem raug xa mus rau cov raj ntev ntev, hluav taws xob welded ntev, cov raj welded, ntawm lwm lub npe.
